The invention relates to a power transmission system in which a specially designed wheel and a compressible drive belt or element engaged in the periphery of the wheel will provide a positive drive regardless of the direction of rotation of the wheel.
Transmission of power by using a flexible and usually endless power transmission element, such as a drive belt or rope, has been used for many years. The conventional drive uses pulleys each of which has a V-shaped groove in which is engaged a V-shaped belt. These belt and pulley systems will transmit power by frictional engagement between the belt and pulley. Since slippage frequently occurs between the drive belt and pulleys when a load is applied, various techniques have been used to increase the friction between the pulleys and belts. Even with these improved techniques that increase the friction and reduce slippage, the frictional forces between the pulleys and drive belt are not sufficient to eliminate the slippage that will occur when a sufficiently high load is applied.
My prior U.S. Pat. No. 4,077,271 discloses a unique design in which the drive wheel has a peripheral surface provided with a plurality of circumferentially spaced impressions for receiving a drive belt or rope. This particular design of my prior patent utilizes a compressible rope or belt that becomes locked in the impressions of the wheel with a resistance equal to the load which is being applied without relying upon friction between the wheel and belt. Slippage in my prior design is eliminated by compression of the drive belt or rope. However, the prior design is expensive to manufacture because of the precise configuration of the impressions in the drive wheel. Moreover, because of the irregular thickness around the circumference of the wheel, the wheel has less dynamic balance and more vibration is produced on the belt by reason of pulses produced during the locking and unlocking of the belt. The vibration in some applications is not desirable, and in addition, the continuous locking and unlocking of the drive belt and drive element produces more rapid wear on the belt.
It is therefore a principal object of the invention to provide an improved design for a drive wheel and drive belt which utilizes compression, rather than friction, and which minimizes vibration and wear and is economical to manufacture.